I really enjoyed this article in New Scientist about Lagrangian points - 'dead zones' in the solar system where opposing forces cancel out gravity and all kinds of items from cosmic dust to asteroids may accumulate becalmed.
NASA's twin STEREO probes, that were launched in 2006 to observe the Sun, are now being tasked to spy on two of these enigmatic spaces on the way to their final destinations (one orbiting ahead of the Earth and the other in its wake).
It's a great example of the serendipitous component to a lot of science: as one of the STEREO lead researchers explains the probes were never designed to look for asteroids (they're actually looking for solar storms) but now they have a golden opportunity to go rock-spotting.
I think the role of serendipity, especially in areas such as space and big science facilities where project lead times are so long, is something that doesn't get talked about enough. It's part of the invisible web that joins up different areas of science and ensures that a new instrument or technical advance in one area can create spin-off benefits for research into something very different.
There's a nice Oxford link to STEREO that I'll be blogging about in detail later in the year.